共查询到20条相似文献,搜索用时 31 毫秒
1.
C. R. Dockery A. R. Stefan A. A. Nieuwland S. N. Roberson B. M. Baguley J. E. Hendrix S. L. Morgan 《Analytical and bioanalytical chemistry》2009,394(8):2095-2103
Systematic designed experiments were employed to find the optimum conditions for extraction of direct, reactive, and vat dyes
from cotton fibers prior to forensic characterization. Automated microextractions were coupled with measurements of extraction
efficiencies on a microplate reader UV–visible spectrophotometer to enable rapid screening of extraction efficiency as a function
of solvent composition. Solvent extraction conditions were also developed to be compatible with subsequent forensic characterization
of extracted dyes by capillary electrophoresis with UV–visible diode array detection. The capillary electrophoresis electrolyte
successfully used in this work consists of 5 mM ammonium acetate in 40:60 acetonitrile–water at pH 9.3, with the addition
of sodium dithionite reducing agent to facilitate analysis of vat dyes. The ultimate goal of these research efforts is enhanced
discrimination of trace fiber evidence by analysis of extracted dyes.
Figure Fitted absorbance response surface for extraction of a direct dye, C. I. yellow 58, using a ternary solvent system. 相似文献
2.
Tsippy Tamiri Rinat Rozin Nitay Lemberger Joseph Almog 《Analytical and bioanalytical chemistry》2009,395(2):421-428
Urea nitrate is a powerful improvised explosive, frequently used by terrorists in the Israeli arena. It was also used in the
first World Trade Center bombing in New York in February 1993. It is difficult to identify urea nitrate in post-explosion
debris, since only a very small fraction survives the blast. Also, in the presence of water, it readily decomposes to its
original components, urea and nitric acid. It is suspected that post-blast debris of urea nitrate can be confused with ammonium
nitrate, the main solid product of urea nitrate thermal decomposition. In a comprehensive study towards identification of
urea nitrate in post-blast traces, a spectrophotometric technique for quantitative determination of urea nitrate was developed,
and conditions were found for extraction and separation of un-exploded traces of urea nitrate with minimal decomposition.
Nevertheless, out of 28 samples collected from a series of three controlled firings of urea nitrate charges, only one gave
the typical adduct ion by liquid chromatography/mass spectrometry analysis. We found that urea nitrate can be extracted from
solid mixtures to organic solvents by using Crown ethers as “host compounds.” The adducts thus formed are solid, crystalline
compounds that can be characterized by microanalysis and spectroscopic techniques.
Figure Adduct formation between urea nitrate and 18-crown-6 相似文献
3.
Ruben t’Kindt Andris Jankevics Richard A. Scheltema Liang Zheng David G. Watson Jean-Claude Dujardin Rainer Breitling Graham H. Coombs Saskia Decuypere 《Analytical and bioanalytical chemistry》2010,398(5):2059-2069
Comparative metabolomics of Leishmania species requires the simultaneous identification and quantification of a large number of intracellular metabolites. Here,
we describe the optimisation of a comprehensive metabolite extraction protocol for Leishmania parasites and the subsequent optimisation of the analytical approach, consisting of hydrophilic interaction liquid chromatography
coupled to LTQ-orbitrap mass spectrometry. The final optimised protocol starts with a rapid quenching of parasite cells to
0 °C, followed by a triplicate washing step in phosphate-buffered saline. The intracellular metabolome of 4 × 107 parasites is then extracted in cold chloroform/methanol/water 20/60/20 (v/v/v) for 1 h at 4 °C, resulting in both cell disruption and comprehensive metabolite dissolution. Our developed metabolomics
platform can detect approximately 20% of the predicted Leishmania metabolome in a single experiment in positive and negative ionisation mode.
相似文献
4.
Electrokinetic sample extraction and enrichment is introduced as a newly developed concept for the analysis of substances
in sludge-type or paste-like matrices. It is based on electrokinetic transport phenomena as electromigration and electroosmosis
occurring when an electrical field is applied to the fresh, wet samples. Problems usually associated to sample drying can
be avoided, e.g., losses of volatile analytes or contamination. We have designed and built a suitable apparatus for electrokinetic
sample extraction and enrichment. Appropriate operating conditions (field strength, buffer composition, concentration, and
volume) were identified in experiments with an artificial sludge model and real-world lake sediments. A proof of principle
of the method was provided by the electromigrative extraction and online enrichment on a solid-phase sorbent disk of an azo
dye from a diatomaceous earth slurry. Electroosmotic extraction and enrichment of a cyanobacterial hepatotoxin at trace levels
was finally investigated as an application example using lake sediments. Rather clean extracts were obtained even with high
organic content sediment samples, as shown by high-performance liquid chromatography with diode array detection.
相似文献
5.
Tuulia Hyötyläinen 《Analytical and bioanalytical chemistry》2009,394(3):743-758
Sample preparation before chromatographic separation is the most time-consuming and error-prone part of the analytical procedure.
Therefore, selecting and optimizing an appropriate sample preparation scheme is a key factor in the final success of the analysis,
and the judicious choice of an appropriate procedure greatly influences the reliability and accuracy of a given analysis.
The main objective of this review is to critically evaluate the applicability, disadvantages, and advantages of various sample
preparation techniques. Particular emphasis is placed on extraction techniques suitable for both liquid and solid samples.
Figure Miniaturised extraction techniques allow sensitive analysis of also small sample volumes. 相似文献
6.
A novel microextraction method is introduced based on dispersive liquid–liquid microextraction (DLLME) in which an in situ
metathesis reaction forms a water-immiscible ionic liquid (IL) that preconcentrates aromatic compounds from water followed
by separation using high-performance liquid chromatography. The simultaneous extraction and metathesis reaction forming the
IL-based extraction phase greatly decreases the extraction time as well as provides higher enrichment factors compared to
traditional IL DLLME and direct immersion single-drop microextraction methods. The effects of various experimental parameters
including type of extraction solvent, extraction and centrifugation times, volume of the sample solution, extraction IL and
exchanging reagent, and addition of organic solvent and salt were investigated and optimized for the extraction of 13 aromatic
compounds. The limits of detection for seven polycyclic aromatic hydrocarbons varied from 0.02 to 0.3 μg L−1. The method reproducibility produced relative standard deviation values ranging from 3.7% to 6.9%. Four real water samples
including tap water, well water, creek water, and river water were analyzed and yielded recoveries ranging from 84% to 115%.
相似文献
7.
Cordes DB Miller A Gamsey S Singaram B 《Analytical and bioanalytical chemistry》2007,387(8):2767-2773
The simultaneous use of several fluorescent reporter dyes in a multicomponent boronic acid-based glucose sensing system is
reported. In one application, two dyes with widely different emission wavelengths are used to report changes in glucose concentration.
A third glucose-insensitive dye was then added to act as a reference dye and provide for a ratiometric correction to the two
reporter dye signals. The inclusion of such a reference dye reduces errors arising from sources such as fluctuations in lamp
intensity and sample dilution.
The simultaneous use of multiple fluorescent reporter dyes 相似文献
8.
Kahina Si-Ahmed Fairouz Tazerouti Ahmed Y. Badjah-Hadj-Ahmed 《Analytical and bioanalytical chemistry》2009,395(2):507-518
In order to study the effect of the nature and the length of the spacer, three mixed 10-undecenoate/phenylcarbamate derivatives
of β-cyclodextrin have been prepared and linked to allylsilica gel by means of a radical reaction. The chiral recognition
ability of the resulting materials, when used as liquid chromatography chiral stationary phases (CSPs), was evaluated using
heptane and either 2-propanol or chloroform as organic mobile-phase modifiers. A large variety of racemic compounds have been
separated successfully on these CSPs (mainly pharmaceuticals and herbicides). Optimization of these separations was discussed
in terms of mobile-phase composition and structural patterns of the injected analytes. The efficiencies of the three prepared
materials were compared to those of previously described perphenylated-β-cyclodextrin column and to analogous cellulose derivative-based
CSPs.
Schematic illustration of the b-cyclodextrin/mandelic acid inclusion complex 相似文献
9.
A rapid, specific, and sensitive method has been developed using molecularly imprinted polymers (MIPs) as solid-phase extraction
sorbents for extraction of trace tetracycline antibiotics (TCs) in foodstuffs. MIPs were prepared by precipitation polymerization
using tetracycline as the template. Under the optimal condition, the imprinting factors for MIPs were 4.1 (oxytetracycline),
7.0 (tetracycline), 7.4 (chlortetracycline), 7.7 (doxycycline), respectively. Furthermore, the performance of MIPs as solid-phase
extraction sorbents was evaluated and high extraction efficiency of molecularly imprinted solid-phase extraction (MISPE) procedure
was demonstrated. Compared with commercial sorbents, MISPE gave a better cleanup efficiency than C18 cartridge and a higher
recovery than Oasis HLB cartridge. Finally, the method of liquid chromatography–tandem mass spectrometry coupled with molecular-imprinted
solid-phase extraction was validated in real samples including lobster, duck, honey, and egg. The spiked recoveries of TCs
ranged from 94.51% to 103.0%. The limits of detection were in the range of 0.1–0.3 μg kg−1.
Chromatograms obtained by direct injection of the spiked egg extracts (5 × 10-3 mmol L−1) and purification with MISPE 相似文献
10.
Núria Serrano José Manuel Díaz-Cruz Cristina Ariño Miquel Esteban 《Analytical and bioanalytical chemistry》2010,396(3):1365-1369
A commercially available screen-printed carbon electrode coated with an ex situ deposited bismuth film (BiSPCE) has been applied
to the determination of Pb(II) and Zn(II) ions in tap water (Barcelona water distribution network) by means of stripping voltammetry
(SV) and stripping chronopotentiometry (SCP). A good reproducibility of the measurements and a satisfactory agreement between
SV and SCP data were observed for both heavy metal ions. Although, in principle, the procedure could be also suited to the
determination of Cd(II), this species was not detected. The results were also consistent with the routine ICP-OES measurements
of the water distribution company, thus confirming the potential usefulness of such BiSPCE disposable devices for the analysis
of heavy metals in natural waters.
相似文献
11.
Eranda Wanigasekara Sirantha Perera Jeffrey A. Crank Leonard Sidisky Robert Shirey Alain Berthod Daniel W. Armstrong 《Analytical and bioanalytical chemistry》2010,396(1):511-524
Four new ionic liquids (IL) were prepared and bonded onto 5-μm silica particles for use as adsorbent in solid-phase microextraction
(SPME). Two ILs contained styrene units that allowed for polymerization and higher carbon content of the bonded silica particles.
Two polymeric ILs differing by their anion were used to prepare two SPME fibers that were used in both headspace and immersion
extractions and compared to commercial fibers. In both sets of experiments, ethyl acetate was used as an internal standard
to take into account adsorbent volume differences between the fibers. The polymeric IL fibers are very efficient in headspace
SPME for short-chain alcohols. Immersion SPME also can be used with the IL fibers for short-chain alcohols as well as for
polar and basic amines that can be extracted at pH 11 without damage to the IL-bonded silica particles. The sensitivities
of the two IL fibers differing by the anion were similar. Their efficacy compares favorably to that of commercial fibers for
polar analytes. The mechanical strength and durability of the polymeric IL fibers were excellent.
相似文献
12.
Christopher T. Kingston Yadienka Martínez-Rubí Jingwen Guan Michael Barnes Christine Scriver Ralph E. Sturgeon Benoit Simard 《Analytical and bioanalytical chemistry》2010,396(3):1037-1044
We have successfully applied coupled thermogravimetry, mass spectrometry, and infrared spectroscopy to the quantification
of surface functional groups on single-walled carbon nanotubes. A high-purity single-walled carbon nanotube sample was subjected
to a rapid functionalization reaction that attached butyric acid moieties to the nanotube sidewalls. This sample was then
subjected to thermal analysis under inert desorption conditions. Resultant infrared and mass spectrometric data were easily
utilized to identify the desorption of the butyric acid groups across a narrow temperature range and we were able to calculate
the degree of substitution of the attached acid groups within the nanotube backbone as 1.7 carbon atoms per hundred, in very
good agreement with independent analytical measurements made by inductively coupled plasma optical emission spectrometry (ICP-OES).
The thermal analysis technique was also able to discern the presence of secondary functional moieties on the nanotube samples
that were not accessible by ICP-OES. This work demonstrates the potential of this technique for assessing the presence of
multiple and diverse functional addends on the nanotube sidewalls, beyond just the principal groups targeted by the specific
functionalization reaction.
相似文献
13.
14.
Lillian Roth Jutta Zagon Anke Ehlers Lothar W. Kroh Hermann Broll 《Analytical and bioanalytical chemistry》2009,394(2):529-537
A new approach for the detection of DNA target molecules is described, using capture probes and subsequent signal enhancement
by a uniform polymerase chain reaction (PCR). Peptide nucleic acid probes were immobilized in real-time PCR-compatible microtiter
plates. After hybridization of biotinylated DNA targets, detection was performed by real-time immuno-PCR, a method formerly
used for protein detection. We demonstrate the feasibility of this strategy for the qualitative detection of DNA oligonucleotides
with a detection limit (LOD) of 6 attomol. Furthermore, the method was applied to PCR-amplified samples from genetically modified
maize DNA (Mon810). A 483-bp DNA fragment was detected in mixture with 99.9% of noncomplementary DNA with a sensitivity down
to the level of attomole.
Figure 相似文献
15.
SPME in environmental analysis 总被引:1,自引:0,他引:1
Recent advances in the use of solid-phase microextraction (SPME) in environmental analysis, including fiber coatings, derivatization
techniques, and in-tube SPME, are reviewed in this article. Several calibration methods for SPME, including traditional calibration
methods, the equilibrium extraction method, the exhaustive extraction method, and several diffusion-based calibration methods,
are presented. Recent developed SPME devices for on-site sampling and several applications of SPME in environmental analysis
are also introduced.
相似文献
16.
The efficiencies of two traditional extraction methods used in Chinese medicine (the decoction method and the maceration method)
were evaluated for the extraction of antioxidants from medicinal plants. A group of medicinal plants possessing nutritious
and tonic functions were chosen as model plants. A commonly used extraction method was used as a reference method. The antioxidant
capacities and total phenolic contents of the extracts were measured by ferric-reducing antioxidant power and Trolox equivalent
antioxidant capacity assays as well as the Folin–Ciocalteu method, respectively. The results obtained indicated that the two
traditional extraction methods could effectively extract antioxidants from medicinal plants. These extraction methods can
be applied to the analysis and purification of antioxidants in plants, respectively. At home, people can use these methods
to extract antioxidants from plants for consumption. In the food industry, these methods could be utilized to prepare crude
extracts from plants containing antioxidants for use as food additives.
Figure Relation and comparison of extraction efficiencies of two traditional extraction methods with the reference method
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Veronica M. T. Lattanzio Michele Solfrizzo Angelo Visconti 《Analytical and bioanalytical chemistry》2009,395(5):1325-1334
The selective enzymatic deacetylation of T-2 toxin to give HT-2 toxin has been investigated in aqueous crude extracts of different
cereals and exploited to develop an analytical method for the determination of the sum of T-2 and HT-2 toxins. The method
has been validated for the analysis of total T-2 and HT-2 toxins in maize, wheat, and oats, showing recoveries from 72 to
97% for maize, from 67 to 84% for wheat, and from 61% to 87% for oats, at spiking levels of 20–400 μg/kg, with relative standard
deviation lower than 10%. Liquid chromatography-tandem mass spectrometry was used for quantitative toxin determination. The
potential biological role of this enzymatic conversion and its perspectives for application in the development of antibody-based
analytical techniques are discussed.
相似文献
18.
Nattikarn Kaewkhomdee Sandra Mounicou Joanna Szpunar Ryszard Lobinski Juwadee Shiowatana 《Analytical and bioanalytical chemistry》2010,396(3):1355-1364
Sequential extraction (water, Driselase, protease XIV) and extraction with simulated gastric and intestinal fluids were proposed
to characterize the binding and the bioaccessibility of chromium in two commercial food supplements obtained by incorporation
of this element into yeast. Chromium in Cr-enriched yeast was found to be hardly extractable with water, Driselase, or simulated
gastric fluid (recoveries of approximately 10–20%), but proteolysis or gastrointestinal fluid digestion released more than
half of the chromium present. Fractionation with size-exclusion chromatography with Cr-specific detection by inductively coupled
plasma mass spectrometry (ICP MS) allowed the distinction of two fractions: one below approximately 1 kDa and one 1–5 kDa;
they contained the entirety of the released Cr with proportions varying as a function of the extracting solution and the origin
of sample. When collected and investigated by reversed-phase high-performance liquid chromatography–ICP MS, the low molecular
mass fraction was found to release Cr(III), whereas the heavier one showed most of Cr bound in fairly stable hydrophobic complexes.
However, an attempt of their identification by electrospray ionization MS/MS and matrix-assisted laser desorption ionization
MS was not successful.
相似文献
19.
20.
András Gergely Péter Horváth György Szász Gábor Veress 《Analytical and bioanalytical chemistry》2009,394(8):2105-2109
A three-step gradient reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the separation
of dehydroepiandrosterone (DHEA), its sulfate ester (DHEA-S), its three C7-oxidized metabolites (7αOH-DHEA, 7βOH-DHEA, 7-keto-DHEA),
and its biosynthetic congeners (androstenedione, testosterone, estradiol, pregnenolone). This new method allows the quantitative
characterization of DHEA metabolism and biosynthetic transformation under given physiological, pathological, or therapeutically
influenced circumstances. Tetrahydrofuran probably acts as a proton acceptor coadsorbent, while isopropanol behaves as a proton
donor during the separation of testosterone, estradiol, and the stereoisomers of 7-OH-DHEA.
Figure Optimized gradient RP-HPLC results in full separation of DHEA from its biosynthetic congeners and metabolites 相似文献